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Rendering a prop - how do I set up IBL?

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    Rendering a prop - how do I set up IBL?

    Hi, I have been reworking an old prop of mine:



    ... now that I have Unreal 4. However, as this is literally me simply downloading it, checking out a couple things, watching a few videos and moving forward ... I'm not very knowledgable yet on using the editor to get any sort of advanced rendering. I had used UDK before, did a cube map once but with weak results. I've worked my materials to the point that I feel it needs to be taken beyond the default setup, have some IBL in there to get some interesting reflections going on to really sell the material. I'm an environment artist simply trying to put a portfolio piece together. My biggest concern is about reflections. While there is plenty of documentation to read about, I'm not seeing much in terms of tutorials. I get much of the theory (as far as I know) but not the node set up, and what to put into what channel, etc. Any help on this matter would be much appreciated. Whether technical or even artistic advise about what the door needs to look better, either way. Thanks.

    #2
    If you're wanting a good overview of reflections through materials a good place to start would be with our information on Physically Based Materials. This is a good source for the basics of the material attributes. There are sliders below some of the material attributes such as roughness, metallic, and specular to give you and idea of how to handle though for your material. The areas you'll probably want to focus with your material on are those to get the results you're looking for out the gate.

    You can also check out a lot of our material setups in Content Examples project from Marketplace > Open Map > any of the Materials Maps and Reflections maps.

    If you're wanting to understand reflections for the environment that goes beyond just your material you can have a look at our Reflections Subway available on the Marketplace. It seems like from your post above that this is the information you stumbled across with the box reflection and sphere reflection.

    I hope this helps.

    If you have any other questions feel free to ask!

    Tim
    Tim Hobson | Learning Resources | Epic Games
    UE4 Documentation

    Comment


      #3
      I've done a lot of research on PBR materials and am certainly up for the possibility that this is the issue ... but I don't believe it is. I believe it is more about the scene set up. I've look at multiple scenes including the subway reflections and am only left confused as I don't see anything in the materials that say "reflection". Reflections seem to "just work" Unreal 4 as long as the materials are there correctly. However I have metal, but no reflections.



      ) I've tried simply placing a sphere around the model with an HDI emissive material, with and without a sphere capture, and no reflections. Note that the HDR is 8000x4000 jpg and Unreal wont let me place it into cube map channels (I would like to know why)

      2) I've gone into the reflections level example, placed my model into the scene, and even created an object that is all black with "1" metalness, but no reflections

      3) I placed a skylight in with a sky map from Unreal's engine assets and received a wash out result of color without seeing the image details at all at any intensity, only more color reflected.

      4) I placed a post process volume over the model with the same sky map and received similar but different results.

      These are just four shots of my recent attempt to figure out Unreal reflections. I had somehow accidentally deleted multiple sky maps out of the engine assets library (some of them it seemed that they turned into material thumbnails simply by double-clicking them). I have no idea at this point about the relevance of capture actors, as I cannot get them to have any effect at all, other than a slight omni light effect with the brightness slider. I'm simply trying to set up a portfolio piece render. Any and help is appreciated. Thanks.

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        #4
        Roughness determines which parts of a mesh should be reflective - less rough means more reflections. Bring an interior or exterior(with more stuff than just a sky and clouds) HDR image into the engine instead of using that sky map and you'll get a better result.

        Click image for larger version

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        Here there is an HDRI in the post prcess and a spotlight, but as you can see the image reflections are more dominant.

        Dont forget to set the skylight source type to Specified cubemap when you use and HDRI. Make sure the HDR image is in HDR format when you import(also, it will be downsized to 512 in game regardless of the size you import at.) And dont forget to use static lighting if you decide to use reclection spheres. Post your material setup if you still run into problems.
        Last edited by Jacky; 08-11-2014, 04:39 PM.
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          #5





          @Jacky: The last image comparison above really tells it. Yeah, it was the gloss level. I didn't see the spheres or builds do anything because my maps weren't glossy enough to show a significant change. You can read, read, read, but until you do it, you don't know it yet.

          @Tim: My words are eaten ... you were definitely right about the materials. My initial post didn't help with enough info as to where I was in my understanding. I guess I assumed that since I studied PBR, had a metalness map, didn't have a physical scene, and was bewildered by the different ways to set up things to reflect in an Unreal 4 scene, that it must be the scene setup that was the issue.

          Seriously, thanks.

          From here I will try some changes to my color and gloss maps. I'm not sure how the color of the metal changes the reflections either. My biggest questions for this forum now is about importing HDRs and the different ways to capture reflections. My HDR is in .jpg format and is giving me a message upon importing (and won't go into the cubemap slot at all). The scene shown above has it on the sphere (static mesh) as an emissive material. How do I have it in the right format? Also, I'm confused about static vs. stationary lighting. If I should use static lights, what does this mean (from the manual):

          "Static light types should not be used together with the Reflection Environment as they will put direct lighting in the lightmap."

          And as well, am I to understand that the skylight only reflects light based on an image, not full-blown image reflections (from the manual):

          "We also get specular from the sky through a Sky Light, but that does not provide local reflections, since the Sky Light cubemap is infinitely far away"

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            #6
            One more question: How do I set up a background for a portfolio render? As soon as I place anything in the background, my lighting changes. In UDK, I could place a sphere in the back with a flat emissive color after baking the lighting. Now when I place it, the lighting becomes overpowering? If the sphere is gray, I get gray washing all around the model and the main light is overblown.

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              #7


              Here are some more of my ongoing experiments and thoughts, having spent several hours with this (there is a near black color sphere (static mesh) in the background surrounding the object in all four):

              1) Static lights destroy the metal reflections here. I'm going to try some full environment builds and see if there is a difference. I'm not sure why the advice to use static lights with spheres.
              2) Ambient cubemap in the post process seems to destroy the AO, like its reflecting it too much from every direction. What is this useful for? The documentation seems to admit that it has limited usage.
              3) I want the AO of the upper left image (or better if that's possible), but the reflections of the two right side images. Is this possible or is it a necessary evil to have less AO with the metal reflections?
              4) Is the skylight used more for colored lights over an environment than for reflections (like a substitute for placing colored lights all over a full environment)? The documentation seems to say so.

              Above all else, I'm having a very difficult time understanding how to control the background color. In Unity there is simply a background color button in the camera settings. Here, there is no such thing (that I know of), I place a sphere around the object, but the minute I make its color above pure black it goes light gray and washes out the lighting on the object by over-brightening. I want to figure out how to place a dark-gray background behind the model.

              Admittedly this is as much me collecting my thoughts at this point as it is asking questions. Any comments, corrections, directions, re-directions, help, suggestions or clarifications?

              Comment


                #8
                When you use reflection spheres and static lighting in an empty environment it is normal that you dont get any reflections. Reflection spheres capture whatever is in the environment. And you cant see skylight reflections when you have a sphere background covering the mesh. The best way to test these to see the difference is make a chrome material(or get the one from starter content), put it on a sphere mesh and toss it into the level.

                Click image for larger version

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                The sun here is movable(reflection sphere works but only as a preview, you wont see the effect in game). The first screenshot has reflection sphere disabled, and an HDR in the post process, intensity 0.1. You can see how it is filling the reflections where SSR cant. The second one is a skylight with the same HDR image, intensity 1.5. The black areas are the angles where SSR cant capture reflections, but HDR is still visible where there is no obsturction which is sky. And the third one is the same skylight with reflection sphere enabled. Reflection sphere fills all the distance SSR cant capture.

                The AO solution in the PP isnt great right now so you may want to go with static lighting if you want the best AO and lighting condition. And that will require you to create a lightmap UV for the mesh of course if you havent already.
                Last edited by Jacky; 08-13-2014, 02:28 AM.
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                  #9
                  This is a lot of help, so thank you. I learned to fix my materials first, then to step back and check my setup with a simple sphere. It's been difficult, but a good learning experience for me.

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